Stable greases containing synthetic gelling agents



United States Patent 1 STABLE GREASES CONTAINING SYNTHETIC GELLING AGENTS Frederick C. Frank, Barnsboro, N. J., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Application September 27, 1952, Serial No. 311,955

12 Claims. (Cl. 252-39) This invention relates to lubricating grease compositions suitable for use over a wide range of operating conditions. More specifically, the present invention is concerned with the stabilization of grease compositions such that they are stable when used or stored at temperatures varying from about 32 F. to about 500 F.

Recently, a new and novel group of grease compositions has been developed from metal soaps of partial esters and partial amides of acidic copolymers of alpha, beta unsaturated polycarboxylic acids or their anhydrides with low molecular weight compounds having a terminal vinyl group (CH=CH2). These grease compositions are described in detail by John I. Giarnrnaria in application Serial No. 311,960 now Patent No. 2,698,297, filed concurrently herewith. While the grease compositions described in said application have an excellent combination of properties and have outstanding performance characteristics, they tend to stiffen on standing. That is, the greases can be milled to a smooth, plastic mass but, on standing they often become stiff and elastic or rubbery. meric materials, incorporated into these greases in relatively small proportions, effectively reduce or even eliminate this undesirable characteristic. In addition, in some instances the plasticizing effect of the polymeric material increases the dropping point of the grease.

It is an object of this invention, therefore, to provide greases containing said metal soaps of acidic copolymers, having a high degree of stability. It is also an object of this invention to provide stable greases having high dropping points, of the order of 400 F. and higher. Other objects will be apparent from the following description.

As indicated, the greases of this invention contain polymeric materials which serve as stabilizing agents. Effective polymeric materials have average molecular weights from about 10,000 to about 100,000, and include the following:

(1) Olefin polymers, such as polymers of alpha monoolefins having up to about eighteen carbon atoms per molecule, typical of which are polymers of propylene, isobutylene, decene; particularly polypropylenes having an average molecular weight of about 100,000, and polyisobutylenes having an average molecular weight of about 100,000; and alkylated polystyrenes, particularly polystyrenes alkylated with Ora-C12 olefins;

(2) Ester polymers such as polymers of alkyl methacrylates, alkyl acrylates, vinyl esters;

(3) Esterified reaction products of an alpha, betaunsaturated dicarboxylic acid anhydride and vinyl acetate, which reactions products are esterified with a saturated aliphatic alcohol containing between about 12 and about 18 carbon atoms in a straight chain; such esteritied products are described by I. I. Giammaria in copending application Serial No. 744,802, filed April '29, 1947, now Patent No. 2,616,851, issued November 4, 1952;

(4) Products obtained by copolymerizing vinyl and/or alkyl ethers with alpha, beta'unsaturated dicarboxylic It has now been discovered that certain poly- 2,737,494 Fatented Mar. 6, 1956 acids or their anhydrides, such product being esterified with primary, normal saturated aliphatic alcohols containing up to about eighteen carbon atoms per molecule; these esterified products are described by I. J. Giammaria in copending application Serial No. 77,288, filed February 18, 1949;

(5) Esters of thiophene-modified, maleic anhydridestyrene copolymers; described by F. P. Otto and O. M. Reifi in application Serial No. 118,708, filed September 29, 1949, and now Patent No. 2,600,798, issued June 17, 1952.

The polymeric materials are used in amounts of the order of from about one per cent to about ten per cent, by weight, of the total grease composition. Preferably, the amount of polymeric material will fall within the range of two to five per cent.

As explained in detail in said application Serial No. 311,960, the novel soaps of the greases there described are metal soaps of partial esters and of partial amides obtained by reaction of an aliphatic alcohol having at least about eight carbon atoms per molecule or an aliphatic amine having at least about eight carbon atoms per molecule, respectively, with an acidic copolymer of a lower molecular weight vinyl compound, such as styrene or vinyl acetate, with an alpha, beta unsaturated polycarboxylic acid or anhydride. Illustrative of such metal soaps are those shown in the following non-limiting examples.

EXAMPLE I Seventy-three and one-half parts by weight of styrene and 49 parts by weight of maleic anhydride were dissolved in 1000 parts by weight of toluene. The resulting solution was heated to 150 F. and 1.23 parts by weight of benzoyl peroxide were added. Heating was continued to about 200 F. where reaction took place as evidenced by clouding of the solution. Heating at reflux (about 220 F.) was continued for one hour. The styrenemaleic anhydride thus formed was partially esterified with a mixture of 93.6 parts by weight of Lorol 5 alcohol and 9.9 parts by weight of n-octadecanol, using 4.54 parts of paratoluene sulfonic acid as catalyst, at 300 F. for two hours. The resulting partial ester had a neutralization number of 121.0.

Lorol 5 alcohol is a mixture comprising 2.8 per cent ndecanol, 61.0 per cent n-dodecanol, 21 per cent of n-tetradecanol, 11.0 per cent of n-hexadecanol and 2.2 per cent of n-octadecanol.

Eighty parts by weight of the partial ester, described above, 371 parts by weight of an acid-refined naphthenic oil (232 S. U. S. at 100 F.) and 8.7 parts by weight of LiOH.H2O dissolved in 78.0 parts by weight of water, were mixed in a suitable grease kettle and heated to 400 F. over a four hour period. The resulting grease was stirred while cooling to room temperature F.). The soap concentration was eighteen per cent.

A portion of the resulting grease was blended with ten per cent by weight of polyisobutylene (20 per cent polymer in oil; average molecular weight of polymer, about 100,000), and with sufficient oil to reduce the soap content to sixteen per cent. The final grease did not stiifen and actually showed a higher dropping point. The dropping point of the grease without polyisobutylene was 280 F.; whereas, the dropping point of the grease with polyisobutylene was above 400 F.

EXAMPLE II U of Ba(OH)2.8HzO and 10 parts by weight of Water were mixed in a grease kettle and heated to 350 F. during a Also, Stenol is a commercial prodct substantially all of which is n-octadecanol.

Table 1 Grease Stabilizing Agent D v op 2mg Example No. Metal Alcohol Or nrninc Acid Copoiymer Polymer g fgggagg l 1 Barium Lorol-5 Aleoholm. Styrene-Maleic 400+ Anhydridc. 2 do do .do Polyisobutylene. 5 (2071 Polymer N0 400+ 3 Lithium do... 280 4 do ..do 400+ 230 Isobutyl Phenol. 230 Poiyisobutylenc. 400+ 8 ..do Lorol- Alcohol 265 (75% by Wt.) and Stenol (25% by Wt.). 9 do do do Polyisobutylene. 10 (20% Polymer No 400+ in oil).

10 Lithium Lorol-5 Alcohol do YesVory 375 (90% by Wt.) Heavy. and Stenol (10% by Wt). 11 do ,do do Polyisobutylene. 1080?? Polymer No 475 in or 12 d0 do do Alkylated Polyd0 N0 .r 300 styrene. 13 (lo do do Polyrnethyl- 5 (40% Polymer No 425 methacrylate. in o 14 Lithium (80% do do No 200 by Wt.). 15 Lithium Salt 0 12-hydroxystearlc do Polyisobutylene. 10 Polymer No 67a Acid (20% by Wt.). in oil).

16 Barium Lorol-5 Alcohol--. do Yes. 400+ 17 do do 1o Polyisobutylene- 5 (20% Polymer No 400+ in oil).

18 Calcium do do N o 400 19 .do do "do Poiyisobutylene. 10 (2037); Polymer No 500+ mol 20 do d0 .-do Alkylated Polydo No r. 450

styrene.

21 do do ..do Yes 300 22 do do do Polyisobutylena. 100017)}, Polymer No 500 moi 23 do do do Alkylated Polyd0 No 465 styrene. 24 d0 do do Polymethyl- 5 (%Polymerln No 475 methaerylate. oil) 25 Lithium soaps of conventional fatty acids No 375 26 do Polylsobutylene- 10 (201% Polymer N0 375 mm 27 do Alkylated Polydo No 375 styrene. 375 28 do Polymethyl- 5(40%Po1ymerin No methacrylate. oil).

1 A. S. T. M. designation: D 56642.

four hour period, and were maintained at 350 F. for a one hour period. The resulting grease was then stirred while it was cooled to room temperature (about 70-80 F.). The soap concentration of the grease was twenty per cent.

Two hundred and sixty parts by weight of the grease described immediately above were blended with thirteen part-s by weight of polyisobutylene (described in Example I), which reduced the soap concentration to nineteen per cent. This grease was smooth and bright and showed no stiffening on standing.

The following illustrative, and non-limiting examples, serve to demonstrate the improvement realized by incorporating a stabilizing agent into a grease of the type described in Examples 1 and II, above. These illustrations are provided below in tabulated form in Table 1.

By Way of explanation, the polyisobutylene, polymethylmethacrylate and alkylated polystyrene polymers shown in Table 1, had average molecular weight of about 100,000.

69 soap.

" as well as elimination of stiflfness, resulting from addition of the isobutylene polymer.

Examples 5 and 6 show that isobutyl phenol is ineffective in eliminating stifiness. In contrast, Example 7 shows an isobutylene polymer eliminates stiffness and increases 0 the dropping point markedly, from 230 to more than 400.

Examples 8 and 9 provide a similar demonstration.

Examples 10 through 13 show that stiffness is banished by each of the polymers incorporated in the grease. However, the dropping point of the grease is increased sub- '5 stantially by an isobutylene polymer and by a methyl furized fats, lead soaps, etc.

.nie ha yla e po ymer, he eas an al yla ed styren pelvm u s a re se in dropp ng Poi t- Examples 14 and '15 show the elfect of an isobutylene polymer on a grease prepared from a mixture of a soap of a partial ester of an acidic copolymer and a soap of a conventional fatty acid. Whilethe grease of Example 14 did not stiffen, its dropping point was materially imp om 2 F- t 3 8 by the polymer- Examples 16 and 17 also show an elimination ofstitfness by the isobutylene polymer. The grease of Example 16 stiffened, and this seemed to increase with time.

Examples 18 through 20 reveal an increase in dropping Po y the iti n of a polyme Examples 21 through 24 show elimination of stifiness and increase in dropping point. It should be noted that the calcium grease of Example 20 did not stiffen, whereas the related grease in Example 21 did stiffen. This difference in behavior can be attributed to the fact that the soap of Example 18 was esterified to the extent of fiftyfi p n n h s an o E ampl 2 was st r fi d t the extent of sixty per cent.

Examples 25 t ou h 28 a inc dedin o der t sh the effect of the several polymers, used in the preceding examples, upon a current commercial grease containing soaps of conventional fatty acids. In no instance was the dropping point of the grease increased by the polymer.

It is to be understood that the greases can also contain other characterizing materials in addition to the polymer stabilizing agents. For example, the greases can contain grease antioxidants such as amines, phenols, sulfides, etc., and lubricity improving agents such as glycerine, free fat, free fatty acids, esters of alkyl and/or aryl acids, sul- All such well-known characterizing materials do not detract from the beneficial properties imparted by the polymers; rather, such characterizing materials serve to impart their customary properties to the grease.

With regard to preparing the greases of this invention, the polymer is added at the last stages of the preparation. That is, after the grease containing a metal soap, or soaps, of a partial .ester or partial amide of the type described above, has been prepared, the polymer is added and is thoroughly dispersed or admixed therein. No improvement is realized when the polymer is incorporated during the preparation of the grease.

I claim:

1. A grease comprising an oleaginous vehicle and a salt in an amount sufiicient to thicken said vehicle to form a grease, said salt being a metal salt of an acidic reaction product obtained by reaction of a compound selected from the group consisting of an aliphatic monohydric alcohol having at least about eight carbon atoms per molecule and an aliphatic monoamine having at least about eight carbon atoms per molecule, with an acidic copolymer of an alpha, beta unsaturated polycarboxylic acid and a low molecular Weight organic compound having a terminal vinyl group and having less than about ten carbon atoms per molecule, such that from about fifty to about ninety per cent of the carboxyl groups of the acidic copolymer are reacted with said compound, said acidic copolymer having a molecular weight above about 1000, the metal of said salt being selected from the group consisting of metals of Groups I through III of Mendeleeffs Periodic System and a small amount, sufiicient to reduce the tendency to stiffen on standing of a grease comprised of said oleaginous vehicle and said salt, of a polymeric material having an average molecular weight from about 10,000 to about 100,000, polymeric material being selected from the group consisting of an olefin polymer; an ester polymer; an esterified copolymer of an alpha, beta-unsaturated dicarboxylic acid anhydride and vinyl acetate; an esterified copolymer of a vinyl ether and an alpha, beta-unsaturated dicarboxylic acid anhydride; an esterified copolymer of an alkyl ether and an alpha, beta-unsaturated dicarboxylic anhydride;

6 a d an st r of t phen -modifi mal ic hy r styrene copolymer.

2. A grease comprising an oleaginous vehicle, a salt (1) of a fatty acid having ten to twenty-two carbon atoms per molecule and a salt (2), in an amount suificient to thicken said vehicle to form a grease, said salt (2) being a metal salt of an acidic reaction product obtained by reaction of a compound selected from the group consisting of an aliphatic monohydric alcohol having at least about eight carbon atoms per molecule and an aliphatic monoamine having at least about eight carbon atoms per molecule, with an acidic polymer of an alpha, beta unsaturated polycarboxylic acid and a low molecular weight organic compound having a terminal vinyl group and having less than about ten carbon atoms per molecule, such that from about fifty to about ninety per cent of the carboxyl groups of the acidic copolymer are reacted with said compound, said acidic copolymer having a molecular weight above about 1000, the metal of said salt being selected from the group consisting of metals of Groups I through III of Mendeleelfs Periodic System, and a small amount sufiicient to reduce the tendency to stiffen on standing of a grease comprised of said oleaginous vehicle and said salts, of a polymeric material having an average molecular weight from about 10,000 to about 100,000, polymeric material being. selected from the group consisting of an olefin polymer; an ester polymer; an esterificd copolymer of an alpha, beta-unsaturated dicarboxylic acid anhydride and vinyl acetate; an csterified copolymer of a vinyl ether and an alpha, beta-unsaturated dicarboxylic acid anhydride; an esterified copolymer of an alkyl ether and an alpha, beta-unsaturated dicarboxylic anhydride; and an ester of a thiophene-modified, maleic anhydride-styrene copoly mer.

3. A grease comprising an oleaginous vehicle, a salt (1) of a fatty acid having ten to twenty-two carbon atoms per molecule, a salt (2) of a fatty acid having less than about six carbon atoms per molecule and a salt (3), in an amount sutficient to thicken said vehicle to form a grease, said salt (3) being a metal salt of an acidic reaction product obtained by reaction of a compound selected from the group consisting of an aliphatic monohydric alcohol having at least about eight carbon atoms per molecule and an aliphatic monoamine having at least about eight carbon atoms per molecule, with an acidic copolymer of an alpha, beta unsaturated polycarboxylic acid and a low molecular weight organic compound having a terminal vinyl group and having less than about ten carbons atoms per molecule, such that from about fifty to about ninety per cent of the carboxyl groups of the acidic copolymer are reacted with said compound, said acidic copolymer having a molecular weight above about 1000, the metal of said salt being selected from the group consisting of metals of Groups I through III of Mendeleelfs Periodic System, and a small amount, sufiicient to reduce the tendency to stiffen on standing of a grease comprised of said oleaginous vehicle and said salts, of a polymeric ma terial having an average molecular weight from about 10,000 to about 100,000, polymeric material being selected from the group consisting of an olefin polymer; an ester polymer, an esterified copolymer of an alpha, beta-unsaturated dicarboxylic acid anhydride and vinyl acetate; an esterified copolymer of a vinyl ether and an alpha, beta-unsaturated dicarboxylic acid anhydride; an esterified copolymer of an alkyl ether and an alphabetaunsaturated dicarboxylic anhydride; and an ester of a tiophene-modified, maleic anhydride-styrene copolymer. 4. A grease as defined by claim 1 wherein the polymer 1s an isobutylene polymer having an average molecular weight of about 100,000.

5. A grease as defined by claim 1 wherein the polymer is a methyl methacrylate polymer having an average molecular weight of about 100,000.

6. A grease as defined by claim 1 wherein the polymer is an alkylated polystyrene having an average molecular weight of about 100,000.

7. A grease as defined by claim 1 wherein the polymer is present in an amount between about one and about ten per cent.

8. A grease comprising a mineral oil of lubricating viscosity, and lithium salts in an amount sufficient to thicken said oil to form a grease, said salts being lithium salts of partial esters obtained by reaction of a mixture of aliphatic alcohols having from ten to eighteen carbon atoms per molecule and predominantly dodecanol and octadecanol with an acidic copolymer of styrene and maleic anhydride having a molecular weight above about 1000, such that about fifty per cent of the carboxyl groups of the acidic copolymer are reacted with said alcohols; said grease having incorporated therewith, a small amount sufiicient to reduce the tendency to stiffen on standing of said oil and said salts, of a polyisobutylene having an average molecular weight of about 100,000.

9. A grease comprising a mineral oil of lubricating viscosity, and calcium salts in an amount sufiicient to thicken said oil to form a grease, said salts being calcium salts of partial esters obtained by reaction of a mixture of aliphatic alcohols having from ten to eighteen carbon atoms per molecule and predominantly dodecanol and octadecanol with an acidic copolymer of styrene and maleic anhydride having a molecular weight above about 1000, such that about fifty per cent of the carboxyl groups of the acidic copolymer are reacted with said alcohols; said grease having incorporated therewith, a small amount sufficient to reduce the tendency to stifien on standing of said oil and said salts, of a polyisobutylene having an average molecular weight of about 100,000.

10. A grease comprising a mineral oil of lubricating viscosity, and calcium salts in an amount sufiicient to thicken said oil to form a grease, said salts being calcium salts of partial esters obtained by reaction of a mixture of aliphatic alcohols having from ten to eighteen carbon atoms per molecule and predominantly dodecanol with an acidic copolymer of styrene and maleic anhydride having a molecular weight above about 1000, such that about fifty per cent of the carboxyl groups of the acidic copolymer are reacted with said alcohols; said grease having incorporated therewith, a small amount sufiicient to reduce the tendency to stiffen on standing of said oil and said salts, of a polymethylmethacrylate having an average molecular weight of about 100,000.

11. A grease comprising a mineral oil of lubricating viscosity, and calcium salts in an amount sufiicient to thicken said oil to form a grease, said salts being calcium salts of partial esters obtained by reaction of a mixture of aliphatic alcohols having from ten to eighteen carbon atoms per molecule and predominantly dodecanol with an acidic copolymer of styrene and maleic anhydride, such that about fifty per cent of the carboxyl groups of the acidic copolymer are reacted with said alcohols; said grease having incorporated therewith, a small amount sufficient to reduce the tendency to stifien on standing of said oil and said salts, of an alkylated polystyrene having an average molecular weight of about 100,000.

12. A grease comprising a mineral oil of lubricating viscosity, and lithium 12-hydroxy stearate (1) and lithium salts (2) in an amount sufiicient to thicken said oil to form a grease, said salts (2) being lithium salts of partial esters obtained by reaction of a mixture of aliphatic alcohols having from ten to eighteen carbon atoms per molecule and predominantly dodecanol and octadecanol with an acidic copolymer of styrene and maleic anhydride having a molecular weight above about 1000, such that about fifty per cent of the carboxyl groups of the acidic copolymer are reacted with said alcohols; said grease having incorporated therewith, a small amount sufiicicnt to reduce the tendency to stiffen on standing of said oil and said salts (1) and (2), of a polyisobutylene having an average molecular weight of about 100,000.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A GREASE COMPRISING AN OLEAGINOUS VEHICLE AND A SALT IN AN AMOUNT SUFFICIENT TO THICKEN SAID VEHICLE TO FORM A GREASE, SAID SALT BEING A METAL SALT OF AN ACIDIC REACTION PRODUCT OBTAINED BY REACTION OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ALIPHATIC MONOHYDRIC ALCOHOL HAVING AT LEAST ABOUT EIGHT CARBON ATOMS PER MOLECULE AND AN ALIPHATIC MONOAMINE HAVING AT LEAST ABOUT EIGHT CARBON ATOMS PER MOLECULE, WITH AN ACIDIC COPOLYMER OF AN ALPHA, BETA UNSATURATED POLYCARBOXYLIC ACID AND A LOW MOLECULAR WEIGHT ORGANIC COMPOUND HAVING A TERMINAL VINYL GROUP AND HAVING LESS THAN ABOUT TEN CARBON ATOMS PER MOLECULE, SUCH THAT FROM ABOUT FIFTY TO ABOUT NINETY PER CENT OF THE CARBOXYL GROUPS OF THE ACIDIC COPOLYMER ARE REACTED WITH SAID COMPOUND, SAID ACIDIC COPOLYMER HAVING A MOLECULAR WEIGHT ABOVE ABOUT 1000, THE METAL OF SAID SALT BEING SELECTED FROM THE GROUP CONSISTING OF METALS OF GROUPS I THROUGH III AND MENDELEEFF''S PERIODIC SYSTEM AND A SMALL AMOUNT, SUFFICIENT TO REDUCE THE TENDENCY TO STIFFEN ON STANDING OF A GREASE COMPRISED OF SAID OLEAGINOUS VEHICLE AND SAID SALT, OF A POLYMERIC MATERIAL HAVING AN AVERAGE MOLECULAR WEIGHT FROM ABOUT 10,000 TO ABOUT 100,000, POLYMERIC MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF AN OLEFIN POLYMER; AN ESTER POLYMER; AND ESTERIFIED COPOLYMER OF AN ALPHA, BETA-UNSATURATED DICARBOXYLIC ACID ANHYDRIDE AND VINYL ACETATE; AND ESTERFIED COPOLYMER OF A VINYL ETHER AND AN ALPHA, BETA-UNSATURATED DICARBOXYLIC ACID ANHYDRIDE; AN ESTERIFIED COPOLYMER OF AN ALKYL ETHER AND AN ALPHA, BETA-UNSATURATED DICARBOXYLIC ANHYDRIDE; AND AND ESTER OF THIOPHENE-MODIFIED, MALEIC ANHYDRIDESTYRENE COPOLYMER. 